1. Field of the Invention
The present invention relates to an image reproduction apparatus for reproducing an image on paper from a digital image signal, and more particularly, an image reproduction apparatus for reproducing an image on paper from a digital image signal obtained by scanning an image or from coded image data supplied from a personal computer. The present invention also relates to a method of reproducing an image and a program for causing a computer to execute the method.
2. Description of the Related Art
In recent years, a digital copying machine capable of dealing with digital image data has appeared. Furthermore, a digital multifunction device has also become popular that has not only a digital copying function, but also other additional functions, such as a facsimile function, a printer function, and a scanner function (examples of such digital multifunction devices may be found, for example, in Japanese Unexamined Patent Application Publication No. 2000-316063 or Japanese Unexamined Patent Application Publication No. 2002-116665).
The digital multifunction device disclosed in Japanese Unexamined Patent Application Publication No. 2000-316063 is an image processing apparatus in which a memory is efficiently shared by a plurality of functions, and a control mechanism including an extension unit is commonly used by the plurality of functions. That is, in this image processing apparatus, resources are used in an efficient manner. FIG. 20 is a block diagram showing an example of a structure of a conventional image processing apparatus. This image processing apparatus includes an image reading unit 1, a sensor board unit 2, an image data controller 3, an image processor 4, a video data controller 5, and an image forming unit 6. The image processing apparatus also includes a process controller 11, a RAM 12, a ROM 13, and an I/O controller 14, wherein those units are connected via a serial bus 10. The image processing apparatus also includes an image memory access controller 21, a memory module 22, and a facsimile controller 24, all of which are connected with the image data controller 3 via a parallel bus 20. The image processing apparatus further includes a system controller 31, a RAM 32, a ROM 33, and an operation control panel 34, which are connected to the image memory access controller 21.
The image reading unit 1 optically reads a document by illuminating the document with light emitted from a lamp and focusing light reflected from the document on an image sensing device (such as a CCD) disposed on a sensor board unit 2 via a mirror and a lens. The light focused on the image sensing device is converted into an electric signal by the image sensing device. The resultant electric signal is converted, in the sensor board unit 2, into a digital image signal and output from the sensor board unit 2. The image signal output from the sensor board unit 2 is input to an image data controller 3.
The image data controller 3 controls transmission of image data among the sensor board unit 2, the parallel bus 20, and the image processor 4, and the image data controller 3 also controls signal transmission between the process controller 11 and the system controller 31, which is responsible for general control over the entire apparatus.
The image signal output from the sensor board unit 2 is supplied to the image processor 4 via the image data controller 3. The image processor 4 compensates for signal degradation that occurs (in the scanner system) in an optical system and/or during a process of quantizing the signal into digital form. The resultant signal is fed back to the image data controller 3.
The image processing apparatus shown in FIG. 20 is configured to handle a job in which image data obtained by reading an image is stored in a memory and the stored image data is used later, and also a job in which image data is not stored in the memory. Those two types of jobs are described in further detail below. An example in which image data is stored in the memory is a job in which one page of document is copied on a plurality of sheets. Another example is a job in which image data obtained by operating the image reading unit 1 only once is stored in the memory module 22, and the image data stored therein is read out a plurality of times. An example in which image data is not stored in the memory is a job in which one page of document is copied on only one sheet. In this case, the image data obtained by reading the document can be directly reproduced without being stored in the memory.
In the case in which the memory is not used, the image data transmitted from the image processor 4 to the image data controller 3 is fed back to the image process 4 from the image data controller 3. In the image processor 4, the image data is subjected to image processing to convert the luminance signal generated by the CCD into an area-modulated signal. After completion of the image processing, the resultant image data is supplied from the image processor 4 to the video data controller 5. The video data controller 5 performs post processing associated with dot distribution on the area-modulated signal and controls the image forming unit 6 by a pulse control signal to reproduce dots on paper, thereby reproducing the image on the paper.
The data flow is described below for the case in which image data stored in the memory is read and subjected to additional processing such as image rotation or image mixing. In this case, image data supplied from the image processor 4 to the image data controller 3 is transferred from the image data controller 3 to the memory access controller 21 via the parallel bus 20. Under the control of the system controller 31, the memory access controller 21 performs controls storing the image data into the memory module 22, conversion of the image data into print data to be used by an external personal computer (PC) 23, and compression/decompression of the image data for the purpose of using the memory in an efficient manner.
When the memory access controller 21 receives the image data, the memory access controller 21 compresses the image data and stores the compressed image data into the memory module 22. The image data stored in the memory module 22 is read out as required. The image data read out from the memory module 22 is decompressed into the original image data and returned to the image data controller 3 via the image memory access controller 21 and the parallel bus 20. The image data supplied from the image data controller 3 to the image process 4 is subjected to image processing. Thereafter, the video data controller 5 generates a control signal in the form of a pulse, thereby controlling the image formation unit 6 in accordance with image data such that the image is reproduced on paper.
In the image processing apparatus shown in FIG. 20, after the image data is subjected to image processing performed by the image processor 4, the image data is supplied to the facsimile controller 24 via the image data controller 3 and the parallel bus 20. The facsimile controller 24 converts the received image data into facsimile data and transmits the resultant data over the communication network such as the public communication line 25. On the other hand, incoming facsimile data received via the public communication line 25 is converted into image data by the facsimile controller 24. The resultant image data is supplied to the image processor 4 via the parallel bus 20 and the image data controller 3. In this case, no particular image processing is performed by the image processor 4. The video data controller 5 performs dot redistribution and controls the image forming unit 6 by a pulse control signal so as to form a reproduced image on paper.
In the case in which a plurality of jobs, such as a copying job, a facsimile transmission/reception job, and a printer output job are performed in parallel, use, by the respective jobs, of various units such as the image reading unit 1, the image forming unit 6, and the parallel bus 20 is controlled by the system controller 31 and the process controller 11. The process controller 11 controls the flow of image data, and the system controller 31 is responsible for general control over the entire system. Use of the respective resources is controlled by the system controller 31. A function such as the copying function or the facsimile function to be executed on the digital multifunction device is specified via the operation control panel 34. The detailed operation conditions of the specified function are also set via the operation control panel 34. The system controller 31 and the process controller 11 communicate with each other via the parallel bus 20, the image data controller 3, and the serial bus 10. The image data controller 3 also performs data format conversion for the purpose of interfacing between the parallel bus 20 and the serial bus 10.
In this image processing apparatus, signals for driving various mechanical parts and signals from/to various sensors are input or output to the process controller 11 via ports under the control of the I/O controller 14. The process controller 11 monitors and processes those signals by means of interruption.
In the case in which copying is performed on only one sheet, it is not necessary to store image data in the memory module 22 via the image memory access controller 21, but it is desirable to store image data because, when a paper jam occurs in the image forming system, the image data stored in the memory module 22 can be used. Besides, if image data is not stored in the memory module 22, it is impossible to form an image on paper such that the image formed on paper is rotated with respect to the original image on a document sheet. That is, non-use of the memory module 22 results in limited use of available functions.
The image processing apparatus has the capability of outputting its operational history for convenience in maintenance of the apparatus. Historical data such as failure history, jam history, and operation history is stored in the RAM 32 or the ROM 33. When the historical data is printed out, the historical data is converted into font data on the memory module 22, and printing on paper is performed in accordance with the font data on the memory module 22. Information printed on the paper makes it possible for a service person to properly do a maintenance job. However, if the memory module 22 is not available, the service person cannot get the information, which results in inconvenience in maintenance.
Japanese Unexamined Patent Application Publication No. 2002-116665 discloses a digital multifunction device in the form of an image forming apparatus having a copying function, a facsimile function, and other functions. In this digital multifunction device, if a wrong side of a document sheet is scanned by mistake, a warning is given to inform a user that the scanned document page is blank. This prevents a blank page from being sent by mistake in facsimile transmission.
In the image processing apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2000-316063, a platform includes resources that are assumed to be shared when the functions of the apparatus are extended into the form of a digital multifunction device. Therefore, when only the copying function is necessary, the apparatus includes unnecessary components, which results in an increase in cost and an increase in power consumption.
In the image forming apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2002-116665, when a blank document sheet is scanned using a sheet-through document feeder, if a black streak image due to paper dust or the like on the sheet-through document feeder occurs in a resultant captured image, the blank document page is incorrectly determined as a correct page, and the page including only the black streak is copied or transmitted.